(a) Field of the Invention
The present invention relates to a sample applicator and, more particularly, to a sample applicator to be used in electrophoresis for applying a sample such as blood serum to a film.
(b) Description of the Prior Art
To analyze blood serum proteins etc. by electrophoresis, it is necessary to apply a sample such as blood serum taken from the patient onto a film such as a filter paper, cellulose acetate film or the like (hereinafter referred to as film). In electrophoresis, a fractionated pattern of sample is formed by energizing the film on which the sample is applied and that fractionated pattern is analyzed. To obtain a correct analyzing result, it is essential to apply the sample onto the film in a uniform straight line.
In the known method for applying the sample onto the film, the sample is sucked into a micropipette and a line of sample is drawn on the film by using a ruler. In such method, however, it is very inefficient and, moreover, it is difficult to apply the sample in a uniform and straight line. To eliminate the above-mentioned disadvantage, a method to use a blood serum applicator is known. As an example of blood serum applicators for that purpose, a blood serum applicator as shown in FIGS. 1A and 1B is known. That is, two thin plates 1 and 1' are arranged face to face by inserting a spacer 2 between them so that ends 1a and 1'a of thin plates 1 and 1' become parallel with each other. To apply a sample by using the above-mentioned blood serum applicator, the sample is absorb into the small gap 3 formed between the ends 1a and 1'a of thin plates 1 and 1' by means of capillarity and, then, applied onto the film. Another example of known blood serum applicators is constructed as shown in FIGS. 2A and 2B. That is, a V-shaped groove 4a is formed at an end of applicator body 4. This applicator is also arranged to absorb the sample into the V-shaped groove 4a by means of capillarity and, then, to apply the sample onto the film. These known applicators have the following disadvantages. That is, irregularity occurs in the absorbed sample because of surface tension of sample absorbed in the gap or groove at the end of applicator and, consequently, the sample applied onto the film becomes uneven. Moreover, if the applicator is held in the state that its end is inclined, the sample moves toward one side and, as a result, the applied sample becomes irregular. Besides, when the sample is applied by an inclined applicator, one-sided contact occurs between the applicator and film. As a result, the sample flows out onto the film from one end of gap or groove which contacts the film at first and, consequently, the applied sample becomes irregular.